High speed hydraulic press system and method



Feb. 2, 1960 o. A. wHEl-:LoN 2,923,130

HIGH SPEED HYDRAULIC PRESS SYSTEM AND METHOD Filed Sept. 26, 1955 ,f 2 Sheets-Sheet 1 ZZ Vacuum /7 Pump 24; Z4! Q Reservoir INVENTOR.y

Feb. 2, 1960 O. A. wHL-:ELoN

HIGH SPEED HYDRAULIC PRESS SYSTEM AND METHOD Filed sept. 2e. 1955 //Z Vt W 2 Sheets-Sheet 2 competitive sheet metal working industries.

United States Patent C)v HIGH SPEED HYDRAULIC PRESS SYSTEM AND METHOD Orville A. Wheelon, Pacific Palisades, Calif., assignor to Douglas Aircraft Company, Inc., Santa Monica, Calif.

Application September 26, 1955, Serial No. 536,384 `s claims. (ci. lso- 51) This invention relates to hydraulic presses of the diaphragm type. Y

Such presses generally include an open-ended shell enclosing a work-carrying tray slidable into and out of the shell through the open end; a material-working diaphragm mounted superadjacent t0, and coextensive with, the tray, and means mounted in the shell superadjacent the diaphragm for urging it workingly against the workable material in the tray, the latter being disposed in the shell operatively subadjacent the diaphragm.

The means for powering the diaphragm usually consists of, or includes a resilient-elastic bag arranged confrontingly to the upper face of the diaphragm and adapted to be hydraulically expanded against same so as to power the diaphragm against the work.

' The initial supplying of pressure iluid to this bag, for

the purpose of first causing the bag and diaphragm to merely till out to the contines of the working chamber, as well as the subsequent powering of the bag, are usually accomplished by a reversible-rotation pump connected to the bag, the reverse action of this pump serving,

in combination with a throttle-valve, to release the powering-pressure from the bag preparatory to its Vevacuation at the end of the bagis cycle.

Subsequent to this release, the contents of the bag are removed by the direct, but necessarily slow, action of a vacuum pump connected directly thereto.

Among these imperfections, this mode of cycling the press falls somewhat short of the rapidity 'demanded of metal-working presses in the modern large-scale, highly By way of example, the most rapid cycle currently achievable by contemporary diaphragm presses is of the order-of 40 secs., which, being somewhat longer than that of the conventional quick-retraction ram type press, has apparently militated against the widespread adoption, to date, of the diaphragm type press.

In contemporary diaphragm presses, further, all proposals to elevate the Working pressure much above 5000 p.s.i. have come to grief on the fact, among others, that in addition to the aforementioned reversible pump, it has been deemed necessary to provide a number of other pressurepumps in order to apply to the bag, after its volumetric filling, that incremental pressure necessary to raise its total pressure to the desired linal magnitude, which may be as high as 10,000 p.s.i., thereby to cause the powered bag to .force the diaphragm formingly against the work in the subadjacent tray.

A large amount of time is consumed by this initial 'phase of the cycle if elevated pressures are to be ap- There are, of course, certainother, Vperhaps not so i consequential, deficiencies in current diaphragm press Gee hydraulic systems, which imperfections will either become apparent, or be made manifest, hereinafter, in disclosing how they are remedied.

In ameliorating these situations, the present invention, in its most comprehensive species, accomplishes the lowpressure volumetric-filling of the bag and diaphragm to all the boundary-surfacesof the working chamber by means of the rather sudden discharge into the bag of a pre-segregated supply of properly pressurized uid, instead of employing the gradual volumetric filling previously achieved by the reversible pump. In one mode of executing this concept, an accumulator is employedifor the initial-filling portion of the fluid, and this accumulator is continually maintained filled, or, if desired, is recharged after each discharge into the bag, by means of a special accumulator filling and recharging system. At a suitable juncture in the initial phase of the bags cycle, therefore, the accumulator automatically fills the bag with fluidv at a pressure of the order of 500 p.s.i. An intensifier pump is provided and is also adapted to be connected to the bag at a suitable subsequent juncture to eiect the powering phase of the operation of the bag, thereby to actuate the diaphragm.

By means of this sub-combination, the final operating, or powering, pressure of the bag can easily be elevated to the order of 10,000 p.s.i. in a very short time.

The length of the press cycle is still further reduced by means for emptying the bag automatically, and with the maximum possible rapidity, at the end of the cycle. Preferably, Vthis concept is executed by means of a preestablished vacuum maintained in a vacuum-enclosure ready to be automatically connected to the bag instantly upon the release of the working-pressure therefrom, as aforementioned. The vacuum enclosure is maintained at as near a perfect vacuum as is feasible by means of a substantially continuously running vacuum pump connected to this enclosure. It is also within the purview of this invention to connect the opposite side of the enclosure to the atmospheric reservoir for the pressure fluid.

' By this system, the duration of an operating cycle of the press is reduced from the previous 40 secs. or longer, to an average of the order of 7 secs.

In a less comprehensive species of the invention, the accumulator and its charging and re-charging pump are dispensed with, as well as the booster, or intensifier pump and the reversible-pump of the previous practice is employed to both fill-out the bag; to power it; and in cooperation with a throttle valve, to release the powering pressure. Hence, although the cycle is not reduced to a duration of 7 seconds, as above, it can be reduced well below that of other diaphragm presses by retention of means, as before, for automatically emptying the bag rapidly at the end of the cycle. Here, again, a pre-established vacuum is maintained in a vacuum enclosure, which is cut-in to the bags exhaust circuit at the end of the cycle. The enclosure is retained at a fairly high vacuum, as before.

Other advances in this art achieved by subject invention will be made manifest as this disclosure proceeds.

Mainly in order to further clarify these and other objectives as well as to render the nature and accomplishments of the invention more concrete, two typical eX- amples of the many specific modes in which the invention may be embodied are representationally depicted in the accompanying drawings and Will be described in detail hereinafter in conjunction with these drawings. It is to be appreciated, however, that such drawings and said description do not speciiically constitute the invention nor in any wise limit the nature and slope thereof except as required by the appended claims defining the essential system diagrammatically;

Fig. 2 is a diagrammatic view of the preferred form of hydraulic system; and

Fig. 3 isa schematic showing of the electrical operating and control system for the system shown in Fig. 2.

The diaphragm-type press plant depicted in Fig, 1 comprises, comprehensively, a press 9 including a working chamber 10 in the upper portion of which is mounted an expansible powering fluid-cell 12, in turn energized by a hydraulic system 11 that embodies the general concepts of this invention.

System 11 comprises a dual nature pressure uid reservoir-andwacuum tank 13. For the purpose of filling out the cell, or bag, 12 and thereby forcibly urging the diaphragm or pad A against the work in the dropped center tray therebeneath, container 13, which is airtight, includes a hand or motor operated pump 14 mounted therein and adapted to pump the fluid content of 1 3 into the bag. This pump, which has a stand-pipe or supply conduit 26 extending to a point near the b ottom of tank 13, can be operated to fill the bag, in a iirst phase of the cycling, to a pressure of the order of 2007 500 p.s.i., which is sufcient to distend the bag and diaphragm against the walls of the working chamber and to force the diaphragm lightly against the work and, in a second phase, at pressure of the order of 1000 p.s.i. or higher, to force the pad formingly against the Work Piece to give it a nal shape. i

From pump 14 a pressure-fluid conductor 15 extends, via a 4-way fitting 16, to the bag. Conduit 15 com; municates with a fluid-pressure gage 24 connected to, the four-way fitting and this conduit also incorporates a two-way globe, or other, valve 17 mounted in the container with an operating wheel or handle protruding there,- from. The two-way valve 17 discharges downwardly through a conduit 20 when the handle of the valve is properly so adjusted as to bypass the output of pumpv 1.4,. Normally, valve 17 is so adjusted as to direct uid from 1 4 onwardly throughV conduit 15 to the bag.

Subsequent to the aforestated volumetric, or distention, filling of the bag, the pump 14 is further rapidly operated to power the bag against the diaphragm, at a pressure of the order of 1000 p.s.i. or higher, as required for the work being performed, in order to cause the diaphragm to forcibly form the sheet material carried in the tray, that is, in the working chamber, around or on the form blocks on which the sheet material is mounted.

Another conduit 22 leads from the four-Way fitting 16 to the container and includes a relief valve, 18 which is normally closed, but is adapted to spring open if the pressure worked up by the pump in line exceeds a predetermined optimum. Valve 18 may hence well consist of or include a spring-loaded ball normally seated to the right in the valve casing, but overcomable to leftward under the vacuum acting on its left face and the excessive pressure on its right face.

These actions terminate the working, or pressure, phase and the evacuation phase of the press cycle. This latter phase, by removing the pressure-fluid from the bag, en ables or electuates the withdrawal of the diaphragm and 'bag to the upper portion of the working chamber to permit the tray to be Withdrawn, with the finished work, from the working chamber, allowing the excess pressure fluid to back-track, as it were, through conduit 22, which includes a vacuum gage 23.

In order to maintain that vacuum in container 13 which is necessary to effect rapid evacuation of the bag to terminate a cycle, a vacuum pump 19 and a suction con- :seaman 4 duit 21 are provided, the latter opening into container 13. Pump 19 is driven substantially continuously by motor means, not shown, but of the conventional nature. This primer, or vacuum pump maintains a vacuum in the space above the liquid level, the vacuum not being of a great magnitude, however, but which vacuum is suficient to effectuate rapid displacement of the contents of the bag. I

When the bag has been powered to the optimum pressure, the pump, to do so, acting against the partial vacuum in chamber 13 to pressurize the bag, any excess uid back-tracking through conduit 22, the relief valve 1S remaining closed, container 13 now contains only a Ismall amount of reserve fluid. The pump 14 being quiescent, the two-way valve 17 is now opened to establish a passage through pipe 20 into the now vacuumized chamber 13. Thereupon, the contents ofthe bag are evacuated therefrom into chamber 13 rather rapidly, conditioning the system for initiating the next cycle.

Although the pump 14 mustV be operated against a partial,` or low-magnitude vacuum, the standpipe 2.6 of the pump extends nearly to the bottom of container 13 and this pump operates. on the displacement principle so that it overcomes thev negative effect of the vacuum on the fluid contents of container 13.

In Fig. ,2, there is representationally shown a hydraulic system for the rapid initial-filling (low pressure, volumetric, distention), the subsequent powering and the rapid evacuation, of the fluid-powering cell which rather substantially shortens the operating cycle of high-pressure hydraulic, diaphragm presses from a time-period hereto,- fore of the order of 40 seconds to atime periodnot greater than of the order of 7 seconds. That is, froml theI time the initial pressure is applied in the system to the time `whenk the cell is empty, a period of about 7 seconds To these and other ends, this System includes an atmospheric reservoir 2 5 forvflltered4 pressure-Huid, the filtering being continually accomplished by means such as a conventiorlall Oil lter- 2,7 through which an electromotor 28 and pump 29 force oil drawn from 25, via a conduit 36, the filtered oil being returned to the reservoir by a return conduit 3 2. The filter is connected, by a conduit as shown, to a filter pressure gage 33 provided for surveillance of the filter-s operation.

llelc, as in the foregoing species, a diaphragm press of the type shown in Fig. 1 is contemplated as being 0perated by a novel hydraulic system, and it includes, in its working chamber, a resilient-elastic, uid expansible powering cell, 34, as before. This cell is loaded by the pressure uid in two stages of operation, a first, or volumetric, filling out of the bag to make it occupy the working chamber of the press and contact all walls thereof and to make the diaphragm Contact with the tray and its contents; and a second, powering or working action. The first action is rapidly accomplished by rapid unloading of a pressure fluid accumulator system (later described) into the b ag at a relatively low pressure of the ,motor 35 driving a pressure pump 37, the intake of which is connected by conduit 54 to the reservoir 25 and discharging toward the accumulator through a conduit 38, an Vuploader valve 39 being connected in parallel to line ,38'and connected to reservoir 25 by a conduit 41 in order to prevent overpressurization of accumulator 4Z'.

Valve 39 operates when and if the pressure output of pump 37 exceeds a predetermined value, say, 50,0 p.s.i., and in order to ,relieve pump 37 and valve 39 of hack pressure or surges from the accumulator, a check valve 40 is provided in line 38 as shown. g

The accumulator 42 is maintained chargedwith uid at 300-500 p.s.i. and to maintain these limits, a relief valve 43 is shunted in the accumulator conduitry and is connectedto reservoir by a conduit 44.

Reservoir 25 is maintained at atmospheric pressure by means of an air-filtering air inlet unit 45.

A' dual-function ll-and-discharge line .47 is connected to the accumulator and includes a T-iitting 46, from which one conduit 49 leads to a three-way, three-posif tion, twin-solenoid pilot operated valve 48 and thence toward bag 34. Valve 48 is one of the well-known, con# ventional Oilgear Companys 3way, 3-position, Vdouble solenoid pilot operated valves in which when solenoid'B is energized, line 50 is connected to line 66 and line A51 is blocked. When solenoid C is energized, line 50 is connected to line 51 and line 66 is blocked. 3 y

Line 38 leads through T 46 to line 47 and the accumulator. The third conduit associated with T 46 leads to an accumulator pressure gage 73. A conduit 50 leads pressure iiuid from the three-#way valve 48 tothe bag in order to suddenly accomplish the rapid volumetricilling thereof from the charged accumulator, initiating a cycle of press-operation. This release is triggered by a limitf switch and suitable electric conductors, not shown but of conventional nature, when the in-going tray strikes this switch at a pre-deterrnined point in its inwardtravel.

A charge suddenly released from accumulator 42` passes by way of conduit 47 through conduit 50 to a simple header 52 which also serves, in another phase of the cycle, as a manifold. In order to drain this conduitry and associated receptacles, if necessary, a globe valve 53 is shunted thereto and is connected by a conduit 69 to reservoir 2S.

The powering-actuation of the bag to force the diaphragm formingly against the sheet-material on the formblocks in the tray is accomplished by means including an electro-motor 55 and a reversible pump 57 driven thereby, the pump, to power the bag, withdrawing fluid from reservoir 25 through a conduit 64. Aconduit 59 serves, on powering the bag, to lead uid at about S200-10,000 p.s.i. toward the bag. Conduit 59 bifurcates as shown, and each fork includes a check valve, one valve 62 being set at about 500 p.s.i. to isolate the motor-pump unit 57 from the accumulator pressure system during the iilling of the bag, thus preventing accumulator surge through 59, for when solenoid B is actuated, line 50, connected to the bag is also opened and this vents the accumulator to manifold 52 through line 50. Thus, the check valve 62 prevents any flow from the accumulator from reaching pump 57. The other valve, 60, is set at 500 p.s.i. also,

so as to then open to enable the continuation of the pressurizing cycle so as to power the bag. An operators control pressure gage 72 is suitably connected to manifold 52 to enable the press-operator to se- I n'order to supply pressure tluid to pump 57 during its reverse operation so as to prevent cavitation during the last stages of the evacuation of the bag, a line 58 is led olf to the right from line 59 and is connected to reservoir 25. In line 58 is a check valve 63 which permits flow through 58 to 57 on this occasion but prevents flow through 58 to 25' during powering of the bag.

A relief valve 83 is provided in a shunt pipe leading to the' left from line 59, to prevent over-pressurization of the bag in the powering phase thereof. Valve 83 is connected to reservoir 25.

A two-way, or flow-and-return conduit 64 connects pump V57 to reservoir 25 andV it serves both to supply x fluid fordischarge by the pump rtothe bag in the powering lect any desired operating pressure for the bag below the setting of relief valve 83.

In order to release the maximum, or diaphragm-powering, pressure from the bag in order to` initiate the final phase of a cycle and so that the bag contents can, with safety, be suddenly evacuated, the reversible motorpump unit 55-57 is reversed by any suitable conventional means, such as a polarity reversing switch, not

shown, but actuated in the well-known mode by the needle of gage 7'2, this reverse-operation of pump 57 thus drawing iiuid through check valve 62 and releasing the pressure in the bag down to 500 p.s.i. so that upon applying the action of the means for establishing a bag-empty- `ingvacuum or suction to the bag, the latter will be at a pressure insufiicient to blast the fluid into the Vacuum tank or to tend to cause the bag itself to be sucked into the conduitry 50, 51, 47, 50 being shown in Fig. 2 as a pipe leading from the bag through header 52 to the exterior of the press.

phase of the bag cycle and to return the fluid to the reservoir during the high-pressure release phase of the cycle.

The quick-emptying sub-combination of the present system Yfor rapidly and automatically evacuating the bag comprises a vacuum tank 65 connected to a vacuum gage 70, tank 65 being adapted to draw thereinto the de-pressurized contents of the bag through conduits 50 and 66, upon release of the powering pressure therein, as above. Tank 65 is maintained at a predetermined degree of vacuum by means of a vacuum pump 67 driven in that direction of rotation that establishes extremely low pressure in the tank 65 when the one side of the tank 65 is connected, via conduit 66 and 3-position solenoid valve 48, as well as conduit 5l), to manifold 52 and the bag.

Means are provided for emptying -the filled vacuum tank of the fluid received from the bag so as to prepare the tank for subsequently receiving the next bag-load, and these means consist of vacuum pump 67, driven by motor 35 and connected to tank 65 by way of conduit 68, the pump 67 discharging by means of conduit 10@ to the reservoir 25. v

A plurality of switches 74, 75, 77, 78, 79, and 84 is provided for controlling and activating the accumulator, bag, and vacuum conduitry at proper junctures in the cycle of the press. These switches are all conventional Barksdale diaphragm actuated, hydraulic pressurized electrical switches, the internal construction of which therefore needs no description. They are connected on the hydraulic side by piping extending to the respective hydraulic apparatuses shown and are connected on their electrical sides by suitable wiring, etc., as shown in Figure 3.

First considering the accumulator, which must not attain a pressure above 500 p.s.i. or below 300 p.s.i., in lorder to maintain these limits there is provided an accumulator pressureswitch 74, preferably one of the wellknown, widely distributed Barksdale switches, which is set at 500 p.s.i. i'

Pressure switch is so connected to the conduitry as to be cut in or automatically function if the accumulator pressure drops below 300 p.s.i., which is the lower limit at which the bag can be properly lled out.

Bag-distending, volumetric filling switch 77, connected by pipe line to the manifold 52, is alsoa Barksdale switch and is so set as to de-energize solenoid C in valve 48 at 350 p.s.i., thereby disconnecting conduit 51 (which leads from T 46 to the three-way valve 48) from conduit 5t), which leads to the manifold 52and the bag', Vto prevent the high pressure from pump 57 from reaching the accumulator.

In order to maintain the high speed bag-evacuating conduitry closed to flow therethrough until the powered bag has been reduced to a safe evacuating pressure, another'Barksdale switch, 78 is provided and connected to solenoid B which it energizes when the powering pressure in the bag has been reduced to such a value that no shock will ensue upon soleno-id B connecting conduit 50 to conduit 66 and tank 65 via the valve 48.

A safety pressure switch 79 is provided and connected Vto the proper point in the manifold 52 and is set to opercircuit to the bag in the powering phase of the cycle. This switch, which is a normally inactive safety device, is` also preferably a Barksdale switch, locked-in at the aforementioned value. The pressure limitation isnormally taken care of by settings on the variable pressure switch on 72.

A Barksdale vacuum switch 84 is provided in association with the vacuum tank 65, and operates when, tank 65 is at a vacuum of 15-20K inches of mercury to operate the vacuum relay aforementioned` and 84 rst, therefore, senses the presence of a full vacuum in 65 and must be closed before automatic cycling will start. When 73 andl 7.0 indicate that the accumulator is charged and the vacuum is established, then 84 automatically shuts olf motor 35.

summarizing, switches 74 and 75 are electrically connected, as shown in Figure 3, to electromotor l35; switch 78 is electrically connected to solenoid C; switchA 77 is electrically connected to solenoid B; switch 79 is electrically connected to motor 55; and switch 84 is.r electrically connected to motor 35 so as to control thevacuum in tank 65. When switches 74 and 84 are both satisied, and read olf stop conditions, motor 35, will thereby be halted; when switches 75 and 84 read off start conditions, motor 35 will thereby be started.

A pressure uid relief line 209 connects pump 37 to reservoir 25 and serves to relieve the pump of tinid if the motor 35 should happen to be rotated in the wrong direction. An unloading line 47-38 leads from the accumulator to the unloading valve 39. A pilot-operation discharge line 400 leads from valve 48 to the reservoir. A safety relief line 90 leads from pump 57 to reservoir 25.

in Figure 3 the electrical system associated with the aforedescribed hydraulic system for the purpose of auto.- rnatically effecting most of the operations of the press is shown in diagrammatic detail. Although some of these electrical components have already been cursorily referred to of necessity in describing the principal subjectmatter of this application-*the hydraulic system-this electrical system will now be described as a complete unit.

The electrical control system for the hydraulic system of the press, as shown in Figure 3, essentially comprises, first describing the mere layout, an electric energy source 112, preferably three-phase, 440 v., 60 cycles, having a conductor path 113 leading toward motor 55, a conductor path 114 leading toward motor 35, a conductor path 115 leading toward the motor 28 which powers filter pump 29 and a control conductor path leading to a step-down transformer 117. A reversing contactor means 116 is suitably interposed in path 113 to enable reversing of motor 55.

In this control circuitry, a starter 118, such as a 3 pole reversible starter, is provided for pump motor 55, and it is in series with a normally open volumetric filling pump .switch 77, with switch 74 for the accumulator and with solenoid B of valve 48, aforementioned.

In the next horizontal line is shown the normally open vacuum switch 84 in series with the vacuum switch relay 120.

A reversing switch 122 for the motor 55 is shown in series in the next horizontal line with a bag emptying switch 78, normally closed, for emptying the contents of the bag into tank 65 and with solenoid C on value 48.

The succeeding horizontal line has accumulator switch 75 is series with the relay 124 operated by switch 75.

A starter contactor 125 for sensing the direction of rotation of motor 55 is provided in the next line of the diagram in series with a relay contactor 127 which closes to assure that motor 35 operates. Then, in series therewith there is provided a relay-contactor 128 which assures that filter motor 28 operates; as well as a relaycontactor 133 f or switch 84 andA a relay-contactor 134 for the accumulatorI pressure switch, which latter relay contactor 134 closes when 35, 65, and 42 are in proper condition. When these close, a signal light 135 is energizevd, vindicating that the entire system is "readyfk or coatlitened for cycling.

In the next succeeding horizontal line, a normally, closed vacuum switch relay contactor 129 is in parallel with a normally closed accumulator pressure switch 130, When thesel are closed, a signal light 132 is illuminated, indicating that the system is` nlotready and the operator must wait until the final automatic adjustment has voccurred before he can manually trigger the cycle, a s by pushing the cycle control button.

An emergency master switch 137 is provided in the next horizontalline of the diagram and is operralgtlel to terminate all operations in casev of need. This line also includes a system, or plant-starting switch 138 which,` when closed, starts motor l55 in reverse and it so runs until the bag, etc., are drained of any remnants of fluid. Switch 138 is in series with a relay contactor 139 operat; ing ofpressure2 pump-forward relay 154, thru relay'14i) the closing of which relay 148 and its associated components then causes the motor 55 to rotate in the reverse direction.

d A contactor 143 is provided in the next lower hor i zontal line of the diagram and is connected in series with a tray-in relay 146 operated by the aforementioned tray-in limit switch to release relay 140 simultaneously with the engagement of the contacts in relay 154, to effectuate motor reversal.

AV cycling initiating switch 144 is connected in series with` contactor 143 and in parallel with. 146 and is conf nected topoints 145, appearing in the next full horizontal lineof the diagram. y

The safety switch 79 for limiting the bag-pressure is, in. the next short horizontal line, connected in parallel with 143, 144 and 146 and both of these short horizontal lines are connected in series to 139, 140 and 142'.

The other set of contacts of the aforementioned double, or twin, contacts safety switch 79 is provided in the next full horizontal line and in series with it are the contact points 145 for the cycling control switch, as well as the vacuum switchs relay contactor `147, the accumulator pressure switchs relay contactors 148, the points 149 of the system starting switch 138, the relay contactor 150 for the tray-in limit switch, and the relay contactor reverse switch for pump motor 55. Relay-.contactors 156 for relay 154 are shown in the short horizontal line dropped below this full horizontal line. Relay 154 operates the forward switch for pump motor 55 as aforementioned. The relay 153 for vacuum switch 84 is shown in the short horizontal line above this full horizont'al line.

In the next full horizontal line are shown elements 155, 158 and 157. Elements 155 and 157 are holding switches for use in starting the motor 28 of filter pump 29, and element 158 is a contactor-unit in parallel with 155 and 157, also for use in starting 28. The relay for cooperation with these elements is shown at '159.

In the succeeding horizontal line, a somewhat similar arrangement, for starting pump motor 35, is shown and comprises holding switches 1'60 and 162 and `a contactor 1'63, as well as a relay 164 operated thereby.

`In the lowermost horizontal line of the diagram there is shown a tray-,in limit switch for operating a tray-in relayv167.

With this electrical configuration, the electrical system functions essentially as follows, reading the second full, horizontal line first and proceeding thereafter in succession to the other horizontal lines. Before the bag-fill? solenoidV B on valve I48 can be opened, the aforedescribed switches and relays, etc., operate to assure that (1 there is a pressure. of 300-500 p.s.i. in the accumulator; (2) motor 55 isY running forwardly; and that the bag-lill," or volumetric filling, switch 77 is closed and operating.

'9 in the next horizontal line, 84 merely senses the amount of vacuum in 35. It is to be noted that in order for solenoid C on valve 48 to vent the bag to the vacuum tank 35, motor 55 and its pump must be running in reverse and that bag emptying switch 78 must have been closed. In the line including elements 75 and 124, 75 senses, or picks up, the accumulators pressure and relay 124 then connects this circuitry and the interlocking circuitry to the proper one of the indicating lights, relay 124 then operating element 148 as well as operating 130 and 134. The lines including signal lights 132 and 135 are merely condition-indicating circuits and inform the attendant as to whether the Vvarious other elements are in that condition or in those positions which they must occupy before the press can be properly operated.

It is to be noted also that when the system-starting switch 1318 is closed and rotates motor '5 in the bagdraining direction, this closing also causes closing of the filter pump motors relay 1'5'9 and the relay 164 for the motor 35. Button 13'8s closing also effects opening of the next line of the diagram immediately below (this line including 152) which opening establishes the fact that pump motor 5'5 is not yet rotating forwardly, and of course this also closes points 149 in this lower line of the diagram.

Regarding the circuits including elements 143, i144, 146 and 7-9, closure of lany one of these circuits will effect reversal of motor 55 so as to release pressure from the bag. Any movement of the tray that is picked up by the tray limit-switches will also reverse the motor 55. Also, any pressure over 5200 p.s.i. closes 79, reversing 55.

The purpose of the circuit that includes elements 7'9, 145, '147, 148, 1'52 and 154 is to control the forwarding relay of the motor y55 and, to do so and pump oil to the bag, the cycle-control switch 144 must be closed, the vacuum switch 84s relay and the relay of the accumulator pressure switch must both be closed and the trayin relay must be closed, assuming that motor 55 is already properly running in reverse. The forward running of motor 55 can be halted by opening the bag-pressure safety switch, aforementioned.

The circuits including elements 157, 155, 158, 160, 162, 163, 165 and 167 are believed to be self-explanatory.

An operating cycle of the bag and associated hydraulic system commences with the bag substantially entirely devoid of fluid but not at a vacuum in its interior. Motor 55 is running in reverse to drain the bag and associated conduits, lbut is soon shifted to forward running by the interlocking circuitry aforementioned. The vacuum tank is also empty and at about 20 inches of mercury, vacuum. The accumulator is occupied by uid at a pressure of about 350 p.fs.i. to 500 p.s.i.

Solenoid B is then actated by switch 77 to connect conduits 51 and 50, whereupon the filled accumulator discharges suddenly into the bag, distending it into contact with all the walls of the working chamber of the cylindrical press, and pressing thereagainst at a pressure of the order of 300-500 p.s.i. This completes the volumetric phase of the cycle.

The powering phase of the cycle is then initiated by means of the motor 5S and high pressure pump 57, as soon as the bag filling pressure gage 72 indicates the predetermined illed pressure in the bag. The motor 55 runs until the gage 72 indicates about 520() p.s.i. forming pressure in the bag, when the variable pressure switch on 72, but not shown, operates the motor reversing switch on motor 55, this switch not being shown but being standard with such motors. This motor reversing switch thus terminates the pumping in of uid to the bag at the end of the powering expansion of the bag against the diaphragm that causes` the latter to form the work. This also reverses pump 57 and releases the high pressure in the bag, preparatory to evacuating the latter. The released pressure fluid is discharged from pump 57 through line 64 to reservoir 2S.

If the pressure in the bag is at the shockless evacuat- V'arrestati ing pressure of less than 500 p.s.i., switch 78 then operates to energize solenoid B to connect conduits 66 and 50, so that the vacuum in tank 65 will result in the now depressurized contents of the bag rapidly transferring into tank 65. The latter, of course, in the meantime has been maintained at a vacuum, but when the vacuum reaches 20 inches of mercury, switch 84 de-energizes motor 35, the laccumulator having, in the interim, been lled byV pump 37, which now also is stopped.

Thus; the accumulator, bag, and vacuum tank are now again restored to the condition proper for the beginning of another cycle.

Although in describing the construction and configuration of two of the presently contemplated embodiments of the invention certain components thereof have been specifically detailed as to their exact geometrical conformations and locations, or their quantitative ratings or dimensions, it is to be understood that such speciiicity is employed mainly in order to render the description more concrete. The actual scope of the invention is set forth in the following claims.

I claim:

l. InV combination: a reservoir for pressure iiuid; a

j hydraulically powered expansible powering-cell; discrete means for accumulating a body of pressurized fluid therein; fluid-pressure establishing means having respective flow-paths connecting same to the reservoir and to the discrete means and operable to occasionally charge said discrete means with pressurized uid and to expand said cell poweringly; means for triggering the charge from said discrete means into said cell in an initial, volumetric filling of the cell; second discrete means for thereafter applying other pressure iiuid to the filled cell in order to forcefully expand the latter; means for releasing the powering pressure from said cell during the subsequent phase of the cells cycle; a vacuum-enclosure adapted to be connected to said cell during the next subsequent phase of the cells cycle; a vacuum pump operatively connected to said vacuum-enclosure for maintaining same evacuated; and means for how-connecting said enclosure to said cell so as to rapidly transfer the contents of the cell into said enclosure in the final phase of the cells cycle and subsequent to the release of said powering pressure; and means for then discharging said vacuum enclosure of its fluid contents so as to condition the apparatus for another cycle.

2. In combination: a reservoir for pressure fluid; a hydraulically powered, expansible powering-cell; a fluidpressure accumulator; fluid-pressure establishing means having respective ow paths connecting same to the reservoir and to the accumulator and operable to continually charge said accumulator; means for releasing the accumulators charge to the cell at a predetermined juncture in order to volumetrically fill said cell; means for thereafter supplying pressure fluid to said cell to ploweringly expand same; a vacuum enclosure adapted to be connected to said cell to initiate the next subsequent phase of the cells cycle; a vacuum pump operatively connected to said vacuum enclosure for maintaining same evacuated; means for connecting said enclosure to said cell for flow from the latter to the former at a predetermined juncture subsequent to the release ofthe powering pressure so as to rapidly transfer the contents of the cell into said enclosure; and means for transferring the contents of said enclosure to said reservoir, at a predetermined juncture previous to the filling of said accumulator, thereby to condition the system for another cycle.

3. In combination: a reservoir for pressure iluid; a hydraulically powered expansible powering-cell; uidpressure accumulator means; means connected to the reservoir and adapted to be connected to said accumulator means to maintain same charged with uid at low pressure; means for connecting said accumulator means to said cell for filling the latter volumetrically; fluid-pressure establishing means having respective flow-paths connectling k same to the reservoir and to the cell and operable Vin ,one of the initial phases of the cells cycle to expand said cell poweringly after same has been volumetrically lled; means Vf or releasing the powering pressure from said cell during the subsequent phase of the cells cycle; a vacuum enclosure adapted to be connected to Vsaid cell during the next subsequent phase of the cells cycle; a vacuum pump operatively connected to said enclosure for maintaining same evacuated; means for connecting said enclosure to said cell at a predetermined juncture subsequent to the release of the powering pressure so as to rapidly transfer the contents of the cell into said enclosure; and means for transferring the contents of said enclosure to said reservoir before said cell is connected to said enclosure. n 4. In combination; a reservoir for pressure fluid; a hydraulically powered, expansible powering-cell; a fluidpressure accumulator; uidfpressure establishing means having respective ow pathsV connecting same to the reservoir and to the accumulator and operable to continually charge said accumulator; means for releasing the accumulators charge to the cell at a predetermined junc ture in order to volumetrically till said cell; means for thereafter supplying presure fluid to said cell to poweringly expand same; a vacuum enclosure adapted to vbe connected to said cell to initiate the next subsequent phase of the cells cycle; a vacuum pump operatively connected to said vacuum enclosure for maintaining same evacuated; means for connecting said enclosure to said cell for ow from the latter to the former at a predetermined juncture subsequent to the release of the powering pressure so as to rapidly transfer the contents of the cell into said en closure; and means for transferring the contents of said enclosure to said reservoir, atv a predetermined juncture previous to the lling of said accumulator, thereby to condition the system for another cycle.

5. A hydraulic operating system for operating an elastic, expansible power-cell, comprising: a fluid reservoir;

yan accumulator; :fluid-pressure establishing means including conductor paths connecting said pressure establishing means to the reservoir and to said cell and y.accumulator so as -to poweringly operate the cell at Va predetermined juncture in the cycle; means for releasing the powering pressure from said cell subsequent to the powered action thereof while leaving the cell volumetrically distended; a substantially evacuated enclosure adaptedvto be connected to the cell during the next subsequent phase of the cycling of the cell; a pump connected to said evacuated enclosure for maintaining same evacuated; and means flow-connecting said enclosure to said cell and constructed and arranged to effect rapid transfer of the contents of said cell into said evacuated enclosure in the nal phase of cycling of said cell; and lsubsequent to the release of the powering pressure thereon; and means for emptying said evacuated enclosure of its iluid contents prior to re-cycling.

References Cited in the le of this patent UNITED STATES PATENTS 2,004,793 Montgomery June 11, 1935 2,195,035 Molloy Mar. 26, 1940 2,311,229 Herbert Feb. 16, 1943 2,345,213 OShei Mar. 28, 1944 2,418,393 Bridgens Apr. 1, 1947 2,541,887 Payne Feb. 13, 1951 2,641,107 Rappl June 9, 1953 2,691,518 Smith Oct. 12, 1954 2,780,918 Rohrscheib Feb. l2, 1957 FOREIGN PATENTS 1,075,570 France Apr. 14, 1954 (Corresponding U.S. 2,771,850, Nov. 27, 1956) 

